*{
  margin: 0;
  padding: 0;
  list-style: none;
  box-sizing: border-box;
}
.main{
  width: 100%;
  height: 100%;
  display: flex;
  position: fixed;
}
.left{
  background: pink;
  width: 150px;
  height: 100%;
}
.right{
  width: calc(100% - 150px);
  background: #ccc;
  height: 100%;
}